1. Field of Invention
This invention is concerned with improvements relating scaffolding of the kind (hereinafter referred to as being of the kind specified) comprising elongate upright members (which usually extend vertically), elongate cross members (which usually extend horizontally) provided with connection members by which the cross members may be connected to the upright members, and diagonal members of braces comprising mounting formations adapted to be interfitted with receiving formations of the connection members. The invention is particularly concerned with scaffolding which is intended for use as shoring (for example) to support shuttering for use in forming concrete floors and the like. In such application, adjustable jacks are provided at the base of the upright members where the supporting ground is not level and/or uneven. Alternatively, or in addition, adjustable jacks are provided at the upper ends of the upright members, the jacks carrying supporting heads which engage the elements to be supported and thus permit the elements to be supported in a predetermined orientation, for example in a horizontal plane, irrespective of variation in the level of the surface upon which the scaffolding is erected.
2. Description of the Relate Art
Examples of scaffolding of this kind are shown in U.K. Patent Specification No. 1,599,646.
The effectiveness of a scaffolding is measured by its load carrying capacity, and the allowable load of a scaffolding is defined as a fraction of its failure load.
In use, scaffolding of the kind specified is subjected to both vertical and horizontal forces. The vertical forces are carried by the upright members, and failure of the upright members, when overloaded, is by buckling.
Additionally, vertical forces may be transmitted between the upright members by the diagonal braces.
Horizontal forces acting on the top of the structure are also transmitted to the upright members by the braces, being resolved into upward and downward components. Thus, not only must the braces be capable of withstanding buckling under compressive load, but they must also be capable of withstanding tension forces.
The buckling values of the elongate structural members are governed by their effective lengths, and can be reduced by the use of stiff, moment-transmitting joints between the members.